This invention generally pertains to a data locking and unlocking method and device, and in particular to a changeable key scheme for securing data.
In the area of data locking systems, a high degree of security as well as limited access is desired. Some prior art data locking schemes are of a mechanical type, such as those used in the typical door lock, or of the type that use magnetic cards which contain the lock combination. The drawbacks of these types of locking systems are that it is possible for an adversary to steal the key or a lock combination. The key can be duplicated and then returned to the owner without the owner's knowledge. The key or combination has now been compromised and can be used until the lock is rekeyed. Thus, unauthorized access to a system or area can be obtained by unauthorized personnel and there would be no knowledge of, or limit to, this unauthorized access. When a mechanical lock is used, each person with access to the secured item has an identical key. This makes it difficult and costly to rekey the lock in case of compromise since many new keys would have to be issued. Further, the key or combination of mechanical systems are constant and cannot be easily changed.
A data encryption/decryption system encrypts and decrypts information under control of a variable called a key variable. Some encryption systems are currently in use which are well-known to those skilled in the art. Thus, when systems use schemes such as the data encryption standard (DES) security is heavily dependant on safe-guarding the key variable which controls the modification of data. If the key variable becomes known to unauthorized personnel, the encrypted data is no longer secure.